Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, yet the description adds real value: it enumerates what is reported, clarifies the interpretation rule (date drift alone is not worsening throughput), documents the noncomparable edge case, and explicitly states no attention reason or notification is created.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Four tight sentences, front-loaded with the core action and followed by output, interpretation, and edge-case notes. Dense but nothing is redundant; each clause carries distinct information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description does the work of explaining what is returned and how to read it, and it covers the noncomparable path and the absence of side effects. For a two-parameter read-only comparison tool this is close to complete, missing only the meaning of the two identifier parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must carry parameter meaning, and it only indirectly does so via 'two owned saved delivery scenarios.' The earlier_id/later_id ordering and UUID format are left entirely to the schema and self-documenting names, with no added semantics such as chronological ordering requirements.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (replay and compare) and resource (two owned saved delivery scenarios), and the scope constraint (same cohort and window) sharpens it beyond a generic compare tool. It does not explicitly name sibling tools like get_feature_forecast or compare_scope_baseline to differentiate, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage conditions: both scenarios must be owned and share the same cohort and window, and results are noncomparable otherwise. But it never states when to reach for this tool versus siblings such as get_feature_forecast or list_feature_forecasts, leaving the selection to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.